1. Field of the Invention
The present invention relates to a linear motor for use in various industrial machinery, such as, e.g., electrical component mounting apparatuses, semiconductor related apparatuses, or machine tools, and suitably used for driving the direct acting mechanism thereof, and more specifically to a moving magnet type linear slider of a suction force offset type equipped with a field permanent magnet as a moving unit and an armature having an armature winding as a stator.
2. Description of Related Art
The following description sets forth the inventor's knowledge of related art and problems therein and should not be construed as an admission of knowledge in the prior art.
FIGS. 6 and 7 show a conventionally available moving magnet type linear slider for use in various industrial machinery, such as, e.g., electrical component mounting apparatuses, semiconductor related apparatuses, or machine tools, and suitably used for driving the direct acting mechanism thereof. FIG. 6 is a plan view of a conventional moving magnet type linear slider, and FIG. 7 is a side view of the linear slider shown in FIG. 6.
In FIGS. 6 and 7, the reference numeral “31” denotes a fixed base, “32” denotes an armature, “33” denotes a table, “34” denotes a field permanent magnet, “35” denotes a linear scale, “36” denotes a sensor head, “37” denotes a slider, “38” denotes a guide rail, “39” denotes a stopper, “40” denotes a motor lead, “41” denotes a linear scale cable lead, “42” denotes a driver, and “43” denotes a sensor holder.
The fixed base 31 is provided with linear guides constituted by sliders 37 and guide rails 38 for movably supporting the right and left sides of the table 33 placed opposite to the fixed base 31 in parallel. Between the linear guides, armatures 32 fixed on the fixed base 31 and field permanent magnets 34 secured to the lower surface of the table 33 and placed opposite to the armatures 32 via a gap are disposed.
The linear scale 35 is secured to the side surface of the fixed base 31 and the sensor head 36 is secured to the side surface of the table 33 via a sensor holder 43 so as to face the linear scale 35 so that the relative position of the table 33 and the fixed base 31 can be detected.
In the conventional moving magnet type linear slider, since the sensor head 36 is secured to the table 33, the linear scale cable lead 41 is configured to move at the time of driving the table 3. When the liner slider is combined with a driver 42, the motor parameter is stored in an internal memory of the driver 42 (see, e.g., Japanese Unexamined Laid-open Patent Publication-No. H06-054516 (FIG. 1)).
In the conventional moving magnet type linear slider, however, since the linear scale 35 is arranged at the one side of the linear slider, the distance L between the thrust central axis G-G of the armature 32 and the central axis S-S at the attachment position of the linear scale 35 is long, causing minute vibrations of the linear scale due to the microvibration of a driven table 3 at the time of controlling the linear motor, which in turn causes such problems that, e.g., the servo gain cannot be increased or the speed ripple becomes large.
The description herein of advantages and disadvantages of various features, embodiments, methods, and apparatus disclosed in other publications is in no way intended to limit the present invention. For example, certain features of the preferred embodiments of the invention may be capable of overcoming certain disadvantages and/or providing certain advantages, such as, e.g., disadvantages and/or advantages discussed herein, while retaining some or all of the features, embodiments, methods, and apparatus disclosed therein.